Wood power to the fore

Denmark has pledged to abandon coal by 2023, and convert its power station network to run on imported and sustainable biomass.

Workers at Denmark’s Avedøre Power plant are now adept at handling biomass

Denmark’s retreat from coal took a new turn in November, with the decision by Dong Energy, the country’s largest power company, to rebrand as Ørsted (after the Danish scientist who discovered electromagnetics). Dong started its move from a ‘black’ to ‘green’ energy a decade ago, with consumption of coal down by three-quarters, and a full phase-out scheduled by 2023.

The scaling back of the use of the fossil fuel in Denmark has been gathering pace over the past couple of years as Dong Energy reduced its number of power plants and converted to firing with biomass instead of coal. The company announced in February 2017 that by 2023 it would no longer use coal in its power stations, and would replace the use of coal with sustainable biomass.

The Danish energy group also divested its oil and gas business in 2017 to Ineos for DK7B (US$1B). Thomas Thune Andersen, chairman of the rebranded group, says: “Our transformation means that we have become too green for our name. Dong, originally short for Danish Oil and Natural Gas, is no longer an accurate description of who we are, or who we want to be.”

Renewable future

“We’ve decided to take the final step and phase out the use of coal at all our power stations,” explains Henrik Poulsen, CEO of Ørsted. “The future belongs to renewable energy and, therefore, we’re now converting the last of our coal-fired power stations to sustainable biomass.” The firm is the first large European energy group to commit to the complete phase-out of coal for electricity and heating production.

Poulsen adds: “Dong Energy will have gone from being one of the most coal-intensive utilities in Europe to being among the greenest energy companies in Europe.” Since 2002, Dong has increased the use of wood pellets and chips at Herning and Avedøre power stations. In 2016, Avedøre and Studstrup converted 100% to wood pellets and straw. In 2017, Skærbæk, near Fredericia, became 100% wood chip burning.

The company has been assessing future solution for its two remaining coal-fired power stations at Asnæs and Esbjerg, including dialogue with the heating customers to convert the two power stations to use wood chips when heating agreements expire at the end of 2017 and 2019, respectively. Pellets and chips are procured from sustainable forestry and residual products such as branches, twigs and thinning trees, as well as sawdust from the furniture and sawmill industries.

In October, work also started on the construction of a biomass-fired plant at Asnæs Power Station in north-western Zealand, which will be connected to the existing district heating networks and the electricity grid. The project includes the installation of a new conveyor system and wood chip storage. The new plant is due to be completed at the end of 2019, when Asnæs will cease to burn coal.

Ørsted is carrying out the DK1.2B conversion of Asnæs following a 20-year agreement with Danish industrial Novo Nordisk and Novozymes and utility Kalundborg Forsyning – which will use the power for their local factories. Thomas Dalsgaard, CEO of bioenergy and thermal power at Ørsted, said: “By 2023, we’ll have phased out all use of coal at our power stations.”

The biomass-fired plant will be built as a separate unit in new buildings at Asnæs. The plant will have a capacity to produce 25 MW of electricity and a total of 129 MW district heating and process steam – and will mainly run on wood chips. The conversion is expected to result in carbon reductions of 800,000 tpa (which corresponds to the annual carbon emissions from some 400,000 cars.)

The move follows the dismantling of Asnæs’s huge 180ft cranes that once towered over Kalundborg – which could lift 32t of coal at a time. Asnæs’s 1961-built Unit 2 has a capacity of 142 MW of electricity and 193 MW of district heating. The 1981-built Unit 5 is Denmark’s largest, with capacity to produce 640 MW of electricity and 308 MW district heating. Ørsted will decide on the future of the units, which are operated alternately, in 2019.

Denmark’s capital is also part of the switch from coal to biomass. Ørsted A/S has started converting the Avedøre Power Station, or Avedøreværket, located south of Copenhagen, to burn only wood pellets. The state of-the-art combined heat and power (CHP) station claims it is one of the world’s most efficient, and has run on a mix of coal, oil, gas and biomass, including wood pellets andstraw.

The CHP plant consists of two units with a total capacity of 793 MW of electricity and 918 MW of heat. The Avedøre 1 unit was built in 1990, primarily burning coal, with a capacity for oil. In 2015, the then Dong Energy announced it would convert the unit from coal, at a cost of DK740M, to burn 1.2 Mtpa of wood pellets.

The 2001-built Avedøre 2 has a 585 MW electricity production capacity and 570 MW of heat – and is one of the world’s most effective CHP units, with 94% energy conversion efficiency. In 2013, the plant installed a 360t crane at a cost of DK70M to unload 800 tph of wood pellets from ship to shore as it heads to 100% biomass by 2027.

Dong and heating com panies Vestegnens Kraftvarmeselskab (VEKS), and Centralkommunernes Transmissionsselskab (CTR) – a partnership of the municipalities of Frederiksberg, Gentofte, Gladsaxe, Copenhagen and Tårnby – signed an agreement in 2013 to allow for the expansion of Avedøre block 2 to run on wood pellets.

Ørsted’s power station at Studstrup, like Avedøre, will also deliver half of the hot water and heat to Denmark’s second city of Aarhus. Nearby Lisbjerg will contribute an additional 20% of the city’s heat needs. Studstrup’s conversion from coal to wood pellets required changes to the fuel storage silo, conveyance system and the boiler, taking 18 months to complete and costing DK1.3B.

Bulk biomass handling at Skærbæk power plant

Transatlantic

Avedøre and Studstrup alone will require 1 Mtpa of wood pellet. Much of the existing supply for Denmark’s biomass needs has come from producers in the Baltics. However, US suppliers – which have enjoyed strong uptake for seaborne exports from Drax in the UK – will be looking to the Danish market. However, while Denmark imported 600,000t of wood pellets from Latvia and 550,000t from Estonia in 2015, North American imports were negligible.

In October, Ørsted inaugurated the DK1.8M biomass-converted Skærbæk Power Station near Fredericia. Built in 1951 as a coal-fired power station, the facility switched to gas 30-years ago. Ørsted and the Danish group TVIS concluded a new heating agreement in 2013 to run until 2037, including the conversion of Skærbæk to biomass by 2017.

Skærbæk took its first shipload of wood chip in April, allowing cranes and conveyor belts to adjust for biomass. The existing quay has been renovated and extended to accommodate bulkers of up to 175m. A new conveying system and two new unloading cranes have also been installed. An open storage facility has a 30m maximum height, and can store up to 80,000 m3 of wood chips.

In June, the then Dong agreed to sell the remaining Unit 3 of Ensted Power Station in Aabenraa, which is located just north of the German border on the east coast. As part of the plan, the power station will be demolished. Dong sold Ensted’s Unit 2 in 2013. The sale of Unit 3 makes way for the entire power station to be demolished, so that the area can be used for other purposes.

Dong sold Ensted to the Aabenraa-based company Rimeco, the steel recycler, which will demolish the station and resell it to the Municipality of Aabenraa. Rimeco expects the demolition to take until 2020. In 2015, Aabenraa port bought 155,000 m2 of land at Ensted Harbour, including quayside and covered halls, as part of its development plans that include expansion of bulk handling capacity.

Read this item in fullThis complete item is approximately 2000 words in length, and appeared in the November/December 2017 issue of Bulk Materials International, on page 6. To access this issue download the PDF here.

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